JPH0786691B2 - Electrophotographic photoreceptor and manufacturing method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in electrophotographic copying machines, optical printers and the like.

2. Description of the Related Art In order to obtain a high-sensitivity photoreceptor in a function-separated type electrophotographic photoreceptor, it is necessary to realize a charge transport layer having a smaller dielectric constant or a larger mobility.

The dielectric constant of the charge transport layer is 3 to 6 in the case of amorphous carbon, and about 3 in the case of an organic photoconductor (hereinafter referred to as OPC). It is difficult to achieve a dielectric constant lower than this, and there is little merit.

On the other hand, the condition imposed on the mobility of the charge transport layer is μτV> d ² (μ is the mobility, τ is the carrier lifetime, d is the thickness of the charge transport layer, and V is the voltage applied to the charge transport layer. Mobility, and when μ is large, the time for carriers to run through the film thickness d of the charge transport layer is _Tr = d ² / μV, and the charge transport layer having a higher mobility μ has a higher process speed. It becomes possible to realize a copying machine and an optical printer having the above.

Amorphous carbon having a small dielectric constant satisfies the condition that it can travel a distance corresponding to the film thickness d of the charge transport layer as a μτ product that represents the travel distance of carriers, and can attenuate the surface potential with a low light amount. it can. However, the mobility μ is small, and it takes time for carriers injected into the charge transport layer to run through the layer, which greatly limits the process speed.

Therefore, as a charge transporting material having a high mobility μ, we have found that the substituent at the para-position of the phenylene group contains at least either a group having a conjugated bond or a group containing a VIb group element, and oxygen or charge. It was proposed to add a receptor. It was also found that this material has a higher mobility when it is an oligomer vapor deposition film having an upper limit of the maximum polymerization degree than when it is a polymer.

Problem to be Solved by the Invention The degree of polymerization is restricted, and the phenylene group in which the degree of polymerization distribution is controlled is a group in which the para-position substituent has a conjugated bond, or VIb
The vapor-deposited oligomer film containing at least one of the groups containing a group element has excellent crystallinity. The size and distribution of the degree of polymerization differ in the size of the microcrystalline region. Their orientation affects the properties of bulk carrier transfer. Therefore, it is necessary to control the film quality to improve the carrier transmission.

Means for Solving the Problem In a function-separated electrophotographic photosensitive member consisting of a photoconductive layer that generates carriers by photoexcitation and a charge transport layer that transports the carriers, the charge transport layer is a phenylene group and the para-position substituent is VIb. X which is an oligomer containing a group element and having a degree of polymerization of 5 or more, and having the fiber axis as the C axis in its crystal system
The ratio of the diffraction intensity of the diffraction surface (001) of the line diffraction to the diffraction intensity of the diffraction surface (200) is as follows, or from the half width of the peak of the diffraction surface (200) of the X-ray diffraction, the Scherrer's formula (A) The size of the microcrystals calculated by the method is 200 A or more.

In order to obtain this film quality, a step of performing heat treatment after film formation is provided. Also, charge acceptors are added to increase carrier mobility.

Action The movement of carriers in the bulk of a polymer is a result of intramolecular conduction and intermolecular conduction, and mobility is improved from both sides. In order to improve the first intramolecular conduction, the broadening of molecular orbitals and the development of the conjugated system accompanying it are guidelines.
Charged solitons, bipolarons, polarons, etc. are considered as conduction mechanisms. To develop a conjugated system, it is necessary to have many π electrons in the main chain skeleton. It is also an effective means to bring a positive charge onto the main chain by exchanging charges with the electron acceptor. Further, it may have a structure in which electron orbits capable of hopping are adjacent to each other even if conjugation along the main chain is not developed.

The second improvement of intermolecular conduction is classified into improvement of crystallinity and orientation. In any case, in order to facilitate the transfer of the carrier to the adjacent polymer, it is necessary that the molecules are spatially densely arranged and that the electron trajectories in which the carriers move have a large overlap.

Intramolecular conduction in a linear polymer having a phenylene group can be improved centering on the π-electron system of the phenylene group. For example, by introducing a group having a conjugated bond between phenyl groups, the π-electron system is broadened. When the VIb group element is interposed, the phenyl groups adjacent to each other on the fiber axis have a twisted arrangement of π electron orbits, and the orbital spread in the fiber axis direction is small. However, the fiber axis tends to take a rigidly extended shape, and the crystallinity remarkably increases. Therefore, carriers move mainly between adjacent molecules, and intermolecular conduction becomes important.

The effect of the length of the molecule on the crystallinity and orientation is large, and the crystallinity decreases due to the length of the molecule, which in turn lowers the hopping probability of carriers and increases the probability of capturing carriers. The molecular length has a length suitable for the most densely arranged molecules as a bulk. By aligning the molecules to this length, intermolecular conduction can be improved. Therefore, there is an optimum value for the degree of polymerization.

By the way, the carrier transmission direction in the electrophotographic photosensitive member is perpendicular to the substrate surface. Therefore, in order to transport the carrier through the membrane by intermolecular conduction, it is necessary to align the fiber axes of the molecules horizontally with respect to the substrate surface. The fiber axis direction is C by X-ray diffraction
When the axis is taken, the (001) diffraction shows a state where molecules are lined up on the substrate surface, and the (200) diffraction shows a state where molecules are lined up horizontally. Therefore, as the ratio of the diffraction intensity of (001) to the diffraction intensity of (200) decreases, the molecules are more horizontally aligned on the substrate surface, and the carrier transfer is improved. Further, the larger the crystal region, the smaller the region or the trap site that obstructs carrier transmission. Therefore, the smaller the half width of each diffraction peak, the more the molecules and microcrystalline regions are arranged on the substrate surface in the direction corresponding to the diffraction, and the carrier transmission is improved.

Example FIG. 1 is a schematic sectional view showing an example of a basic electrophotographic photosensitive member according to the present invention. The electrophotographic photosensitive member shown in FIG. 1 is a support 1 as an electrophotographic photosensitive member.
On top, there is a charge transport layer 2 and a photoconductive layer 3, said photoconductive layer 3 having a free surface 4 on the one hand.

In the present invention, a linear polymer having a phenylene group may be one having a structure as shown in FIG. Further, it may be a copolymer composed of an arbitrary combination of monomers having a structure raised therein.

FIG. 3 is an X-ray diffraction of the para-phenylene sulfide vapor deposition film which is an example of FIG. X-ray source is CuKα wavelength λ = 1.5
It is 418A. The paraphenylene sulfide film was formed by a resistance heating method from a raw material powder having a single degree of polymerization. The polymerization degrees of the oligomers in the figure are 4, 5, and 6.
The diffraction plane of (001) is at 2θ = 3 to 4 °, and the diffraction peak shifts according to the molecular length corresponding to the length in the fiber axis direction. Approximately, the (001) plane spacing is C = 5 ×
It is proportional to n (A) and the degree of polymerization n. Also, there is a peak corresponding to (200) diffraction near 2θ = 21 °. The a-axis direction corresponds to the molecular interval, and does not change significantly depending on the degree of polymerization, and is constant at about 8.5 A.

The charge acceptors to be added include I ₂ , Br ₂ , Cl ₂ , ICI, and IB.
r, (NO ₂ ) BF ₄ , (NO ₂ ) PF ₆ , (NO ₂ ) SbF ₆ , HClO ₄ , H ₂ SO ₄ , HN
^{_{O 3, HSO 4 -, AgClO}} 4, Fe (ClO 4), BF 3, FeCl 3, FeBr 3, Al
_{Cl 3, InCl 3, InI 3} , ZrCl 4, HfCl 4, TeCl 4, TeBr 4, Te
_{I 4, SnCl 4, SnI 4} , SeCl 4, TiCl 4, TiI 4, FeCl 4 -, AlCl 4
^- , AsF ₅ , SbF ₅ , NbCl ₅ , NbF ₅ , TaCl ₅ , TaI ₅ , MoCl ₅ , Re
_{F 6, IrCl 6, InF 6} , UF 6, OsF 6, XeF 6, TeF 6, SF 6, Se
There are F ₆ , WF ₆ , WCl ₆ , and ReF ₇ .

The charge transport layer 2 is formed by a vacuum vapor deposition method, an ion cluster beam method,
It may be directly formed on the surface of the substrate by a dip method, an electrodeposition method or the like, or a film may be formed by extrusion forming powder,
A method of fusion bonding to the substrate surface may be used.

In the present invention, when an amorphous layer containing silicon having high hardness is used as the photoconductive layer 3, the photoconductive layer 3 has a-
Si (: H: X), a-Si _1-y C _y (: H: X) (0 <y <1), a-Si
_1-y O _y (: H: X) (0 <y <1), a-Si _1-y N _y (: H: X) (0
<Y <1), a-Si _1-z Ge _z (: H: X) (0 <z <1), a- (S
i _1-z Ge _z ) _1-y N _y (: H: X) (0 <y, z <1), a- (Si _1-z Ge _z )
_1-y O _y (: H: X) (0 <y, z <1), or a- (Si _1-z Ge _z ).
_1-y C _y (: H: X) (0 <y, z <1) as a single layer or a laminated layer of these. It can also be used when y is continuously changed.

For forming a-Si (: H: X), which is the photoconductive layer 3 containing silicon, SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiF ₄ , SiCl ₄ , SiHF ₃ ,
Plasma CVD method using a source gas of Si atoms such as SiH ₂ F ₂ , SiH ₃ F, SiHCl ₃ , SiH ₂ Cl ₂ , and SiH ₃ Cl, or targeting polycrystalline silicon, Ar and H ₂ (further F ₂ Alternatively, a reactive sputtering method in a mixed gas of Cl ₂ may be used) is used. In addition, a-Si _1-y C _y (: H: X) (0 <y <1), aS
i _1-y O _y (: H: X) (0 <y <1), a-Si _1-y N _y (: H: X)
To create (0 <y <1), CH ₄ and C were further added as carbon sources.
₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ , C ₂ H ₄ , C ₃ H ₆ , C ₄ H ₈ , C ₂ H ₂ , C ₃ H ₄ , C ₄
Hydrocarbons such as H ₆ and C ₆ H ₆ , CH ₃ F, CH ₃ Cl, CH ₃ l, C ₂ H ₅ Cl, C
Allyl halides such as ₂ H ₅ Br, CClF ₃ , CF ₄ , CHF ₃ , C ₂ F
_6, C ₃ F ₈ or the like freon, is mixed with the silicon source gas using a raw material gas of C atoms, such as fluoride benzene _{C 6 H 6-m F m} (m = 1~6) in the plasma CVD method, Alternatively, the reactive sputtering method is used by mixing with a sputtering gas such as Ar. Further, O ₂ , CO, CO ₂ , NO, NO _{2 and the} like are used as the oxygen source, and N ₂ , NH ₃ , NO and the like are mixed and used as the nitrogen source.

In addition, when Ge is added to a-Si (: H: X), GeH ₄ , Ge ₂ H
₆ , Ge ₃ H ₈ , GeF ₄ , GeCl ₄ , GeHF ₃ , GeH ₂ F ₂ , GeH ₃ F, GeHCl
A gas such as ₃ , GeH ₂ Cl ₂ or GeH ₃ Cl may be mixed with the above Si atom source gas to form the plasma CVD method. Furthermore, in the present invention, the a-Si (: H: X),
a-Si _1-y C _y (: H: X) (0 <y <1), a-Si _1-y O _y (: H: X)
(0 <y <1), a-Si _1-y N _y (: H: X) (0 <y <1),
Alternatively, the conductivity can be controlled by adding impurities to these films added with Ge to obtain desired electrophotographic characteristics. Examples of p-type impurities that give p-type conductivity include B, Al, Ga, and In belonging to Group 10b of the periodic table, and B, Al, and Ga are preferably used to give n-type conductivity. The n-type impurities include N belonging to Group b of the periodic table,
There are P, As, Sb and the like, and P and As are preferably used.

As a method of adding these impurities, in the case of p-type impurities, B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H ₁₁ , B ₆ H ₁₂ , B ₆ H ₁₄ , B
_{F 3, BCl 3, BBr 3} , AlCl 3, (CH 3) 3 Al, (C 2 H 5) 3 Al, (iC 4 H
₉ ) ₃ Al, (CH ₃ ) ₃ Ga, (C ₂ H ₅ ) ₃ Ga, InCl ₃ , (C ₂ H ₅ ) ₃ In,
In the case of type impurities, N ₂ , NH ₃ , NO, N ₂ O, NO ₂ , PH ₃ , P ₂ H ₄ ,
PH ₄ I, PF ₃ , PF ₅ , PCl ₃ , PCl ₅ , PBr ₃ , PBr ₅ , Pl ₃ , As
_{H 3, AsF 3, AsCl 3} , AsBr 3, SbH 3, SbF 3, SbF 5, SbCl 3, S
In the plasma CVD method, a gas such as bCl ₅ or a gas obtained by diluting these gases with H ₂ , He or Ar is used as a source gas such as the above-mentioned C atom or Si atom to be used at the time of forming each film. It can be used as a mixture, and in the reactive sputtering method,
It may be used by mixing with Ar, H _2, F ₂ , or Cl ₂ .

The organic semiconductor of the photoconductive layer 3 includes (1) phthalocyanine pigment (referred to as Pc), for example, metal-free Pc, XPc (X = Cu, N).
i, Co, TiO, Mg, Si (OH ₁₂ , etc.), AlClPcCl, TiOClPcC
l, InClPcCl, InClPc, InBrPcBr and the like. Further (2)
Azo dyes such as monoazo dyes and disazo dyes, (3) penylene pigments such as penylene acid anhydrides and penylene acid imides, (4) indigoid dyes, (5) quinacridone pigments, (6) anthraquinones, pyrenequinones, etc. Polycyclic quinones, (7) cyanine dyes, (8) xanthene dyes, (9) charge transfer complexes such as PVK / TNF, (10) eutectic complexes formed from pyrylium salt dyes and polycarbonate resins, (11) azurenium There are chloride compounds.

A vacuum deposition method, a dip method, an ion cluster beam method, an electrodeposition method or the like is used for forming these organic semiconductors.

When the photoconductive layer 3 is a non-single crystal layer containing chalcogen atoms, the following combinations are possible.
Ge-S, Ge-Se, Ge-Te, Ge-P-S, Ge-P-Se, Ge
-P-Te, Ge-As-S, Ge-As-Se, Ge-As-Te, Ge-
Sb-S, Ge-Sb-Se, Ge-Sb-Te, Ge-As-Te-Se, Ge
-As-S-Te, K-Ca-Ge-S, Ge-Te-Sb-S, etc., or a chalcogenide glass containing Si instead of Ge, and Ge-Si-As-Se, Ge-Si. -As-Te chalcogenide glass is raised.

At this time, the charge transport layer 2 has a thickness of 5 to 50 μm, preferably 10
˜25 μm, and the film thickness of the photoconductive layer 3 is 0.5 to 10 μm, preferably 1 to 5 μm.

In the present invention, in order to further improve the electrophotographic characteristics, the support 1 is interposed between the support 1 and the charge transport layer 2 shown in FIG.
A barrier layer may be provided in order to effectively prevent carriers from being injected into the charge transport layer 2.

As the material for forming the barrier layer, Al ₂ O ₃ , BaO, BaO ₂ , Be
O, Bi ₂ O ₃ , CaO, CeO ₂ , Ce ₂ O ₃ , La ₂ O ₃ , Dy ₂ O ₃ , Lu ₂ O ₃ , C
r ₂ O ₃ , CuO, Cu ₂ O, FeO, PbO, MgO, SrO, Ta ₂ O ₃ , ThO ₂ ,
Metal oxide such as ZrO ₂ , HfO ₂ , TiO ₂ , TiO, SiO ₂ , GeO ₂ , SiO, GeO or metal nitride such as TiN, AIN, SnN, NbN, TaN, GaN, or WC, SnC, TiC, etc. Of metal carbide or SiC,
Insulators such as SiN, GeC, GeN, BC, and BN, and heat-resistant organic compounds such as polyimide, polyamide-imide, and polyacrylonitrile are used.

Further, in order to improve cleaning property, abrasion resistance or corona resistance, it is preferable to form a surface coating layer on the free surface 4 in FIG. Suitable materials for the surface coating layer include Si _x O _1-x , Si _x C _1-x , Si _x N _1-x , G
e _x O _1-x , Ge _x C _1-x , Ge _x N _1-x , B _x N _1-x , B _x C _1-x , Al _x N _1-x
(0 <x <1), and inorganic materials such as carbon and layers containing hydrogen or halogen therein.

Example 1 As a linear polymer having a phenylene group, oligoparaphenylene sulfide (hereinafter referred to as OPS
Was formed on a mirror-polished aluminum substrate by a vacuum evaporation method.

The raw material powder used for vapor deposition changed the polymerization length. Polymerization was carried out by the method of Hawkins (Macromole. 9 (1976) 189), and 5 kinds of polymerization degree were prepared from 4 to 8 in the melting point range of 150 ° C to 285 ° C. The polymerization conditions are such that 1,4-bisthiophenylbenzene, which is a raw material for oligomerization, is 340 to 36 in air.
Heat treatment was performed at 0 ° C. At this time, an oligomer having a degree of polymerization of 4 or more is formed by the action of oxygen in the air. At this point, the raw material powder is a multi-component powder, but the powder components were separated by utilizing the difference in solubility in several kinds of solvents. After this separation, recrystallization was further performed to obtain oligophenylene sulfide powders having different degrees of polymerization as single components. A film having a thickness of 10 μm was formed by a vacuum vapor deposition method using five kinds having a degree of polymerization of 4 to 8. The film forming conditions at this time were the same, the degree of vacuum was 10 ⁻⁵ Torr or less, the substrate temperature was room temperature, and the crucible temperature was 300 to 400 ° C.
The conditions that affect the crystallinity after film formation are the substrate temperature and the crucible temperature. When the substrate temperature is increased, the migration of molecules on the surface of the substrate increases and the crystal region expands. Further, the increase of the crucible temperature leads to the increase of the film formation rate and the expansion of the amorphous region as a result if the setting is lower than the decomposition temperature of the molecule. In this embodiment, the speed is set to 5 A / sec or less. On the other hand, the orientation of the microcrystalline region with respect to the substrate surface also changes under the above two conditions.

The X-ray diffraction spectrum of the vapor-deposited oligophenylene sulfide film having a degree of polymerization of 4, 5, and 6 immediately after vapor deposition is shown in FIG. In order to check the carrier transfer efficiency, Au parallel electrodes were formed on the vapor-deposited film formed on the insulating substrate, and its spectral sensitivity characteristics were evaluated. The evaluation conditions were: applied electric field intensity 5 × 10 ³ V / cm, irradiation light intensity 4
It is 0 μw / cm ² . The results are shown in FIG. In this electrode configuration, optical carrier transmission is parallel to the substrate surface. On the other hand, the electrophotographic characteristics of this vapor-deposited film were measured on the film on the Al substrate surface. Oligomeric phenylene sulfide alone has an absorption peak at 360 nm,
There is no absorption band in the visible range. Therefore, the light irradiation was performed with a xenon lamp containing an ultraviolet light component. As a result, the half-exposure amount (E1 / 2) is 850lxsec, 220lxsec, 130l for the degree of polymerization of 4, 5 and 6.
It became xsec.

What influences the sensitivity is the size of the crystal region and its orientation. The size of the crystal region can be evaluated by Scherrer's formula (A). As the characteristic diffraction peaks, the (001) diffraction surface (2θ = 3 to 4 °) and the (200) diffraction surface (2θ = 2
Pay close attention to 1 °). From these, it is possible to evaluate the size of the crystal regions lined up vertically on the substrate and the size of lined up horizontally. Further, each orientation ratio can be estimated directly by the ratio of these two peak intensities.

In order to control the crystallinity and orientation, the vapor deposition film of each polymerization degree was heat-treated in vacuum. A film with a degree of polymerization of 4 is 70 ° C, and a degree of polymerization of 5 is 7
The polymerization degree was 0, 100 ° C, and the degree of polymerization 6 was 70, 100, 150 ° C. Here, the melting points of the respective degrees of polymerization are 110, 150 and 180 ° C. Changes in orientation ratio during this period are shown in Table 1-1, changes in crystal size of two peaks are shown in Table 1-2, changes in half-exposure amount of electrophotographic characteristics are shown in Table 1-.
3 shows. Fig. 4 shows the photocurrent change of the Au parallel electrode sample when irradiated with 360 nm.

As is clear from Tables 1-1, 2, 3, and 4, when the vertical orientation with respect to the substrate surface increases, carrier conduction in the substrate surface horizontal direction increases, and conversely, the substrate surface horizontal orientation increases with the substrate surface. Carrier transmission in the vertical direction is improved. Therefore, in the structure of the electrophotographic photosensitive member, the increase of (200) diffraction is associated with the improvement of sensitivity.

The function-separated electrophotography was composed of a combination of a 150 ° C. heat-treated film with a degree of polymerization of 6 and a hydrogenated phthalocyanine evaporated film. Negatively charged structure, hydrogenated phthalocyanine 2000A on Al substrate surface
After the film formation, a 10 μm oligophenylene sulfide film is deposited and heat-treated. As a result of the evaluation of the electrophotographic characteristics, an initial charging potential of 800 V for a corona voltage of 6 kV, a half-exposure amount of white light of 0.8 lxsec and a residual potential of 30 V were obtained.

Example 2 In this example, the orientation and crystallinity were controlled by changing the deposition conditions of the oligophenylene sulfide raw material powder having a polymerization degree of 4, 5, 6, 7, and 8. The vapor deposition rate was controlled by the height of the crucible temperature and was set to four types of 1, 5, 10, and 20 A / sec. The substrate temperature is room temperature, 100 ° C, or 150 ° C. The film thickness was set to 10 μm as in Example 1, and a 2 μm-thick film of As ₂ Se ₃ containing a chalcogen atom was formed thereon as a charge generation layer.
The film formation was performed by a vacuum evaporation method and the substrate temperature was 100 ° C.
As a result, a positively charged function-separated type electrophotographic photosensitive member can be constructed. Changes in orientation ratio after vapor deposition of oligophenylene sulfide are shown in Table 2-1, and changes in crystal size are shown in Table 2-2. The electrophotographic characteristics after forming the charge generation layer are uniquely improved by the increase of the polymerization degree, and the film having the polymerization degree of 8 and the vapor deposition rate of 1 A / sec is the best. Further, when the charge generation layer is formed, it is subjected to a vacuum heat treatment at 100 ° C. The half-exposure amount was 0.6 lxsec for white light. Furthermore, it improved to 0.55 lxsec by heating at 150 ℃.

Example 3 The charge generation layer was an amorphous layer containing Si atoms, and the charge transport layer was oxygen-doped polyparaphenylene sulfide (hereinafter referred to as PP).
Called S. ), Oligoparaphenylene sulfide (OP
S). The difference in film quality was examined from the size of the microcrystalline region of the (200) diffraction peak.

The film formation of a-Si: H was performed by the plasma CVD method. Board,
Installed in a parallel plate type capacitively coupled plasma CVD device with a 6-inch discharge electrode, and the inside of the reaction vessel was 5 × 10 ^-6 Torr.
After evacuating to below r, the substrate was heated and controlled to a constant temperature in the temperature range of 150 to 200 ° C. SiH ₄ gas in the reaction vessel, 50sccm,
H ₂ gas introduced 250sccm mixing, 0.2～1.0Tor the container pressure
r, 13.56MHZ high frequency is deposited under the condition of electric power 40-80W, a
-Si: H layer was formed as a photoconductive layer of 1.0 μm.

On this charge generation layer, a PPS film having a thickness of 10 μm was heated and fused in an air atmosphere at 285 ° C. Then 290 ℃ oxygen 100
%, The film was heat-treated for 6 hours to dope oxygen into the film. On the other hand, the OPS film is a vapor deposition film with a polymerization degree of 6. The size of the crystal obtained by X-ray diffraction after lamination and the half-exposure amount were evaluated. The OPS has a crystallite size of 400 A, which is about four times that of oxygen-doped PPS. The electrophotographic sensitivity of the OPS film is 0.6 lx.
It is improved compared to sec and PPS 1.01xsec. Especially, the residual potential is directly related to the carrier mobility, and the OPS is
Greatly improved to 30V or less.

Example 4 TCNQ (7,7,
8,8, -Tetracyanoquinodimethane) was added. In this example, after vapor deposition was performed using a polymerization degree of 6 as the OPS raw material powder, the addition amount TCNQ of 5 wt% was diffused in the gas phase. An azurenium salt compound was used for the photoconductive layer formed on this charge transport layer. 1,4-dimethyl-7-isopropyl azulene and P- dimethylamino cinnamaldehyde was dissolved in tetrahydrofuran, acid _{(HX, X = ClO 4,} BF 4, Br,
I) is reacted while being cooled to 10 ° C or lower, and this solution is
Azurenium salt compound 1- (P-dimethylaminocinnamylidene) -5-isopropyl-3,8-
A dimethylazulenium salt was obtained. This was mixed with butyral resin, dispersed in butyl acetate, applied on the charge transport layer in an amount of 0.1 to 5.0 μm, and dried at 70 ° C.

The azurenium salt has excellent photoconductivity in the wavelength region of 400 to 900 nm, and particularly has a sensitivity peak at a long wavelength of 700 nm or more and can be applied to a printer using a semiconductor laser as a light source. Among the above four kinds of azurenium salts, those containing I (iodine) as an acid are 0.65 lxsec, 800
It showed a good sensitivity of 0.36 lxsec for red light of nm.

EFFECTS OF THE INVENTION According to the present invention, in a function-separated electrophotographic photosensitive member including a photoconductive layer that generates carriers by photoexcitation and a charge transport layer that transports the carriers, the charge transport layer is a phenylene group para substituent group. Is an oligomer having a VIb group element and a degree of polymerization of 5 or more, and the diffraction plane (200) of the diffraction intensity of the X-ray diffraction plane (001) when the fiber axis is taken as the C axis in the crystal system (200 By setting the ratio of 1) to the diffraction intensity to 0.15 or less, an electrophotographic photosensitive member with high sensitivity and low residual potential can be obtained. In addition, the diffraction system (20
By setting the size of the microcrystals calculated from the half width of the peak of (0) according to Scherrer's equation to 200 angstroms or more, an electrophotographic photoreceptor having high mobility can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an electrophotographic photosensitive member in one embodiment of the present invention, FIG. 2 is a view showing X-ray diffraction of oligomers having different degrees of polymerization in Embodiment 1 of the present invention, and FIG. Is a diagram showing the degree of polymerization dependence of the spectral sensitivity of the oligophenylene sulfide vapor-deposited film in the same Example, and FIG. 4 is the sensitivity characteristic when the oligophenylene sulfide vapor-deposited film in the same Example is subjected to heat treatment. It is a figure showing change. 1 ... Support, 2 ... Charge transport layer, 3 ... Photoconductive layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Watanabe 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP 63-276058 (JP, A) JP 64-2062 (JP, A)

Claims (9)

[Claims] 1. A function-separated electrophotographic photosensitive member comprising a photoconductive layer that generates carriers by photoexcitation and a charge transport layer that transports the carriers, wherein the charge transport layer is a phenylene group and a para group is a VIb group substituent. An oligomer containing an element and having a degree of polymerization of 5 or more, and the ratio of the diffraction intensity of the diffraction plane (001) of X-ray diffraction to the diffraction intensity of the diffraction plane (200) with the fiber axis as the C axis in the crystal system. Is 0.15 or less, an electrophotographic photoreceptor. 2. A function-separated electrophotographic photoreceptor comprising a photoconductive layer that generates carriers by photoexcitation and a charge transport layer that transports the carriers, wherein the charge transport layer is a phenylene group, and the substituent at the para position is a VIb group element. It is an oligomer having a polymerization degree of 5 or more, and is calculated from the half-width of the peak of the diffraction plane (200) of X-ray diffraction with the fiber axis as the C axis in the crystal system according to the Scherrer's formula below. Size of microcrystals D = 0.9λ / βCOSθ (A) (D is the size of microcrystals, λ is the wavelength of X-rays, β is the full width at half maximum of the diffraction line in Angstroms, and θ is the diffraction surface ( An electrophotographic photosensitive member having a Bragg angle of 200) of 200 A or more. 3. The electrophotographic photosensitive member according to claim 1, wherein the substituent at the para-position of the phenylene group in the charge transport layer is sulfur oligophenylene sulfide. 4. The electrophotographic photoreceptor according to claim 1, wherein an electron acceptor is added to the charge transport layer. 5. The electrophotographic photosensitive member according to claim 1, wherein the photoconductive layer includes a non-single-crystal layer containing a chalcogen atom. 6. The electrophotographic photosensitive member according to claim 1, wherein the photoconductive layer includes an amorphous layer containing Si or Ge atoms. 7. The electrophotographic photosensitive member according to claim 1, wherein the photoconductive layer includes an organic semiconductor layer. 8. A step of lowering the ratio of the diffraction intensity of the diffraction plane (001) of X-ray diffraction to the diffraction intensity of the diffraction plane (200) by heat treatment after forming the charge transport layer. The method for producing an electrophotographic photosensitive member according to claim 1, which is characterized in that. 9. The electrophotography according to claim 2, further comprising the step of reducing the half-value width of the peak of the diffraction plane (200) of X-ray diffraction by heating after forming the charge transport layer. Manufacturing method of photoconductor.